The food and pharmaceutical industries have recognized for some time the advantages of recovering the organic membrane portion, and in some cases the non-organic hard mineral portion of broken egg shells. The broken egg shells typically are produced by so-called “egg cracking” establishments, where typically the albumin or white of eggs and the yolks of the eggs are separated from the hard egg shells of the eggs for a variety of purposes. Such purposes may include the provision of liquid or frozen whole egg product which may be used by commercial food preparation establishments, commercial bakery establishments, and so on. In other cases, the albumin and the yolks of the eggs are separated one from the other for further processing, as is well known to those skilled in the art.
However, this results in the vast accumulation of broken egg shells, and problems of disposal of the same. One of those problems is the matter of the sheer volume of the recoverable broken egg shells. For example, studies have shown that in Canada over 60 tonnes of broken egg shells are discarded every day. Of course, in United States, such accumulation of broken egg shells per day is considerably greater. This results in severe issues surrounding the disposal of broken egg shells in landfill locations. Not only is there a significant accumulation of volume of the disposed egg shells, thus hastening the exhaustion of the capacity of landfill sites to accommodate waste from other sources, there is the problem surrounding the fact that disposed broken egg shells contain significant organic matter.
Of course, that organic matter is the organic membrane portion of the broken egg shells, which is adhered to the non-organic hard mineral portion of the broken egg shells. The presence of such organic material in landfill site may cause health hazards, may result in gas evolution in time, and may attract unwanted insects and animals to that landfill site.
This fact is further exacerbated because when a significant volume of broken egg shells is disposed of, there may be considerable void space within the disposed accumulation of broken egg shells simply because the irregular shapes of the curved pieces of broken egg shells will not easily nest one with the other thereby leaving void spaces disbursed throughout the discarded egg shells. This, of course, further exacerbates the problem of consumed volume of the landfill site, unless and until heavy rollers or earth moving equipment are driven over the disposed broken egg shells, so is to crush them.
There is, of course, the known fact that organic membrane portion of broken egg shells may be separated from the non-organic hard mineral portion of the broken egg shells, but to date no energy efficient apparatus or method has been developed to do so. Neither has there been an apparatus or method developed which results in substantially 100% yield of the organic membrane portion from the non-organic hard mineral portion of the broken egg shells.
The desirability for supply of separated organic membrane portion of broken egg shells to the food processing and pharmaceutical industries is because of the fact that a very high proportion of the organic membrane is protein matter, including collagens and many other types of protein matter.
Of course, it is also recognized that certain members of the food processing industry may find some use for the hard, non-organic, mineral portion of broken egg shells because of the significant calcium carbonate content thereof, as well as other mineral content such as phosphorus and other trace elements. but only if the hard mineral portion of the broken egg shells is substantially if not completely devoid of organic matter, and only if the hard mineral portion of broken egg shells is provided in finely ground or powder form.
Thus, markets exist in the food processing and pharmaceutical industries for the supply of highly refined, food grade or pharmaceutical grade organic membrane portions of broken eggs, and food grade or pharmaceutical grade ground or powdered non-organic hard mineral portions of broken eggs. It is to satisfy such requirements that the present invention is directed.
The inventors herein have unexpectedly discovered that they may take advantage of the distinct differences between the low specific gravity of the membrane portion of broken egg shells, typically below 1.0, and the relatively high specific gravity of the hard mineral portion of broken egg shells, which is typically in the range of 2.7 to 3.0. In doing so, the inventors can at least partially abrade finely divided particles of broken egg shells which have been ground, and then introduce the ground egg shell particles in the form of a slurry into one or more separating tanks within which a gentle upward serpentine flow of water will cause separation of the membrane portion from the hard mineral portion of the finely divided ground egg shells. The separated bits or pieces of the membrane portion will then become entrained and/or float in the water within the tank in the upper regions thereof. Moreover, the separated hard mineral portion of the finely divided ground egg shells will settle to the bottom of the separating tank, notwithstanding the upward flow of water from a dewatering device which is returned to the separating tank and flows past a plurality of overlapping vanes in an upward, serpentine flow pattern.